Lubricating compositions



United States Patent LUBRICATING COMPOSITIONS Paul R. McCarthy, AllisonPark, and Thomas R. Orem,

Blawnox, Pa., assignors to Gulf Research & Development Company,Pittsburgh, Pa., a corporation of Delaware No Drawing. ApplicationFebruary 12, 1954, Serial No. 410,026

11 Claims. (Cl. 25249.7)

This invention relates to improved lubricating compositions and to theprocess of preparing them and, more particularly, to the class oflubricants existing as plastic solids or jellies.

Grease-like compositions having good lubricating properties can beprepared by dispersing compounds of bentonite with organic bases in alubricating 011. Not all of the lubricating compositions thus prepared,however, are resistant to leaching by water The preparation ofbentonite-organic base compounds is described in U S. Patent No.2,033,856, issued March 10, 1936. These compounds are prepared bybringing together the bentonite and the organic base in the presence ofaqueous mineral acid to effect base exchange. The organic bases shouldpreferably be titratable with mineral acids. Among the reactive basesare many alkaloids, and cyclic, aliphatic, and heterocyclic amines. Someof the preferred bentonite-organic base compounds are prepared bybringing together a bentonite clay and such organic bases as aliphaticamines, their salts, and quaternary ammonium salts. Examples of suchamines and salts are: decylamine, dodecylamine, tetradecylamme,hexadecylamine, octadecylamine, hexadecyl ammonium acetate, octadecylammonium acetate, dimethyldioctyl ammonium acetate, dimethyldidodecylammonium acetate, dimethyldodecylhexadecyl ammonium acetate, d1-methyldicetyl ammonium acetate, dimethylhexadecyloctadecyl ammoniumacetate, dimethyldioctadecyl ammonium acetate and the correspondingchlorides and quaternary ammonium chlorides. The organic bases employedshould be such as to impart substantial organophilic properties to theresulting compounds. The amines and salts listed above producebentonite-organic base compounds suitable for use in producinggrease-like compositions, but the bentonite-organic base compoundsproduced from the lower molecular weight bases, i. e., bases containingto 20 carbon atoms are preferred in that they are less expensive thanthe compounds prepared from the higher molecular weight bases. Thelubricants prepared from an oil and a bentonite-organic base compoundcontaining 10 to 20 carbon atoms have excellent lubricating propertiesbut they have the disadvantage of being easily leached by water. Thus,until now, lubricants prepared from an oil and a bentonite-organic basecompound containing 10 to 20 carbon atoms could not without excessiveloss of the lubricants be used where the lubricants might come incontact with water.

We have discovered that lubricants consisting essentially of adispersion of a compound of a bentonite and an organic base containing10 to 20 carbon atoms in an oil can be, improved particularly withrespect to their water-leaching characteristic without afiecting otherdesirable lubricating properties by dissolving in the oil a polymerselected from the group consisting of polymerized ethylene, polymerizedesters of acrylic acid and polymerized esters of alpha-methacrylic acid.Thus, we have found that a dispersion of a compound of a bentonite andan organic base containing 10 to 20 carbon atoms in a solution of an oiland a polymer selected from the group consisting of polymerizedethylene, polymerized esters of acrylic acid, and polymerized esters ofalphamethacrylic acid results in lubricants having improvedwater-leaching characteristics.

In compounding the compositions of the present invention, variouscompounding and blending procedures may be used. In accordance with apreferred embodiment of the invention, the polymer is first dissolved inthe 2,704,276 Patented Mar. 15, 1955 oil by gradually adding thebentonite compound with stirring at a temperature of about 140 F.Dispersion of the bentonite compound in the polymer-containing oil canbe facilitated by the use of one or more solvating agents. Suitablesolvating agents are polar organic com pounds such as organic acids,esters, alcohols, ethers, ketones, and aldehydes, especially lowmolecular weight compounds of these classes. Examples of suitablesolvating agents are ethyl acetate, acetic acid, acetone, methylalcohol, ethyl alcohol, benzoyl chloride, butyl stearate, cocoanut oil,cyclohexanone, ethylene dichloride, ethyl ether, furfural, isoamylacetate, methyl ethyl ketone, and nitrobenzene. Ordinarily, only a smallamount of such agents is required; however, as much as about 50 per centby weight based on the amount of the bentonite compound can be used.

The mineral oil ingredient in the compositions provided by thisinvention may be any of the hydrocarbon oils of lubricating grade, suchas customarily used in compounding greases. The oil may be a refined orsemi-refined parafinio, naphthenic-, or asphaltic-base oil having aviscosity of about 50 to 4,000 SUS at F. If desired, a blend of oils ofsuitable viscosity may be employed instead of a single oil, by means ofwhich any desired viscosity within the range of 50 to 4,000 SUS at 100F. may be secured. The viscosity of the oil has little effect on thedropping point of the compositions, but more viscous oils producecompositions having greater stickiness and adhesive properties than dothe lighter oils. The oil content of the compositions prepared accordingto this invention may comprise about 75 to about 95 per cent or more byweight of the total composition. The particular oil as well as the exactamount of oil employed depends upon the characteristics desired in thefinal composition.

The polymerized ethylene is a polymerization product of ethylene havinga molecular weight of about 1,000 to 30,000 or more. Polyethyleneshaving a molecular weight within this range are characterized by thefollowing approximate characteristics:

Softening point, C. Viscosity at C., poises 1 10 These polymerizedethylene compounds are obtained by the thermal or catalyticpolymerization of ethylene at high pressure. The method of forming thepolymers is not a part of the present invention.

The polymerized esters of acrylic acid and alpha-methacrylic acidemployed in accordance with the invention are preferably prepared asdescribed in U. S. Patent No. 2,091,627, issued August 31, 1937, byheating the monomeric esters at 70 to 100 C. in the presence of a smallamount of a polymerization catalyst such as peroxides or ozonides. Theesters can be polymerized and then added to the oil or the esters can beadded to the oil and then polymerized. Esters suitable for the purposeof this invention are prepared by the esterification of acrylic acid oralpha-methacrylic acid with a monohydric alcohol containing at least 5carbon atoms, i. e., the amyl, hexyl, heptyl, octyl, nonyl, decyl,lauryl, myristic, cetyl and octadecyl esters of acrylic acid andalpha-methacrylic acid. The esters are preferably those derived from thestraight chain monohydric primary saturated alcohols containing from 8to 18 carbon atoms. When an ester is mentioned it is understood, ofcourse, that a mixture of esters is also intended since many of thecommercial alcohols, particularly the long-chain aliphatic alcohols,contain a mixture of alcohols. Likewise, the polymerization productsused in accordance with the invention may be a mixture of two or morepolymers. For example, we may use a mixture of polymerized n laurylalpha methacrylate, n-myristic alpha methacrylate andn-cetyl-alpha-methacrylate. Instead of a simple mixture of polymers, wecan use co-polymers which result when a mixture of two or more of themonomeric esters is polymerized. The method of forming the esters andthe method of forming the polymers are not a part of the presentinvention.

The polymers of ethylene, alkyl acrylates, and alkyl alpha-methacrylatesare employed in an amount sufficient to increase the water-resistantcharacteristic of the lubricant and insufiicient to substantially changeother desirable characteristics. This amount usually corresponds toabout 0.4 to 5.0 per cent by weight based on the weight of the totalcomposition.

The polymerized methacrylic acid esters can be used in their undilutednormally viscous state; however, from the standpoint of the ease inhandling these materials, both during their preparation and duringsubsequent use, it is preferred to employ an inert solvent to render thepolymers less viscous. Thus, polymer concentrates having any desiredviscosity can be prepared by dissolving the polymer in various inertsolvents such as toluene,

lubricating oil, hydrocarbons boiling in the gasoline boiling-pointrange, and the like. The amount of solvent employed will depend, ofcourse, upon the particular polymer and the particular solvent as Wellas upon the viscosity of the concentrate desired. Polymer concentratessuitable for the purpose of this invention can comprise about to about55 per cent active ingredient, that is, about 75 to about 45 per centneutral solvent, without deleteriously affecting the beneficialproperties of the lubricating compositions. The polymerized methacrylicacid esters can be employed in amounts between about 0.4 and 5.0 percent by weight based on the Weight of the lubricating composition. Itwill be understood, of course, that when polymer concentrates are usedthe amount of concentrate used will be an amount sufiicient toincorporate between about 0.4 and 5.0 per cent by weight of the polymerin the composition. In other words, if a concentrate containing per centactive ingredient is used, the amount of said concentrate would bebetween about 1.0 and 12.5 per cent by weight based on the weight of thelubricating composition.

Suitable polymerized esters for the purpose of this invention arecommercially available under the trade name Acryloid." Materialsmarketed under this trade name are understood to be a mixture ofpolymerized esters of methacrylic acid and have a molecular weight rangeof about 10,000 to about 25,000. Because of the ditficulty encounteredin determining the true molecular weight of a polymer of this type,inspection standards are frequently established with reference to theviscosity of a standard quantity of polymer in a solvent such astoluene. Thus, the molecular weights of polymers of the same chemicaltype can be compared by means of viscosity determinations of standardsolutions. Viscosities generally can be determined much easier thanmolecular weights and at least for laboratory control purposes areindicative of the relative molecular weights of various polymers. Forexample, the relative molecular weights of the various polymers can beexpressed in terms of centistoke viscosity at 100 F. of a 30 per centsolution of polymer in toluene. On this basis, we can use polymers Whoserelative molecular weight is between about 140 and about 375centistokes.

The bentonite compounds employed in preparing the bentonite-organic basecompounds for use in accordance with the invention are compoundscomposed of a montmorillonite mineral in which at least a part of thecation content of the mineral has been replaced by an organic base.Clays that swell at least to some extent on being contacted with waterand contain as a primary constituent a mineral of the group known asmontmorillonites are generally referred to as bentonites. Such clays,which contain exchangeable alkali metal atoms either naturally or aftertreatment, constitute the raw materials employed in makingbentonite-organic base compounds used in the compositions of thisinvention. So far as known, all naturally occurring montmorillonitescontain some magnesium and certain of them, as exemplified by Hectorclay, contain such a high percentage of magnesium that they largely havemagnesium in the place of the aluminum content characteristic of themore typical montmorillonites.

The amount of the bentonite-organic base compound used may vary overwide limits depending upon the particular oil with which it is to beblended and upon the properties desired in the final lubricatingcomposition. While we prefer to use amounts in the order of about 3 to20 per cent by weight, it should be understood that depending upon theconsistency of the composition desired, less than 3 per cent or morethan 20 per cent of the bentonite compound can be employed. When abentonite compound is mentioned, it is understood, of course, that oneor more of such compounds is intended.

When it is desired to produce compositions having improved oxygenstability, we advantageously employ a small amount of a diaryl amine. Asexamples of some of the diaryl amines which may be used in thecompositions of this invention may be mentioned diphenylamine, phenylalpha-naphthylamine, phenyl beta-naphthylamine, alpha alpha-, alphabeta-, beta beta-dinaphthylamines, and the like. Other diaryl amines aswell as their derivatives wherein one or more hydrogen atoms on one orboth of the aromatic nuclei are replaced by a substituent group may beused. The substituting group may, for example, be one selected from theclass of aryl, alkyl, amino, aryloxy and alkyloxy radicals, so long asthe presence of the substituent does not render the diaryl amineinsoluble in oil, or soluble in water or otherwise adversely aifect theetfectiveness of the diaryl amine. The amount of the diaryl amineemployed will depend to a large extent upon the severity of theconditions to which the composition is subjected, as well as theparticular diaryl amine used. For instance, when the composition issubjected to prolonged use under oxidizing conditions, such as underextreme temperature and pressure, the diaryl amine requirement will bemuch greater than when relatively mild operating conditions are encountered. Generally, however, the amount of the diaryl amine employedis between about 0.1 and 1.5 per cent by weight based upon the weight ofthe total composition. In any case, an amount sufiicient tosubstantially inhibit oxidational deterioration is employed.

In order to illustrate the improved water-resistant properties of thecompositions of the present invention, a number of lubricatingcompositions were prepared. In preparing these lubricating compositions,a lubricating oil base having a viscosity of approximately 650 SUS at100 F. was prepared by mixing parts by wei ht of acid-treated Texas oilhaving a viscosity of 500 SUS at F. with 5 parts by weight of naphthenictype residual oil having a viscosity of 175,000 SUS at 100 F. Variousamounts of polymerized ethylene were then added with stirring toseparate portions of the lubricating oil base. The polymerized ethylenewas a solid having a molecular weight of about 20,000. A commerciallyavailable polymerized methacrylic acid ester was added to additionalportions of the oil base.

The polymerized methacrylic acid ester employed in preparing acomposition of the invention for test purposes was a commerciallyavailable concentrate containing approximately 40 per cent by weight ofactive ingredient. The active ingredient is believed to be polymerizedlaurylalphamethacrylate. The active ingredient in a 30 per cent toluenesolution has a relative molecular weight when expressed in terms ofviscosity at 100 F. of centistokes. Typical properties of the 40 percent commercially available concentrate are as follows:

Gravity, API 27 Specific gravity 0.89 Flash point, F. 400 ASTM pourpoint, F -l-20 Viscosity:

cs. at 100 F 5,750 SUS at 100 F 27,500 cs. at 210 F 671 SUS at 210 F3,100 Color, ASTM 2 Neutralization No 0.10

When diluted with three parts mineral oil having a flash point of 400 F.

When solution of the polymer in each of the samples was complete, 6.5parts by weight of a compound of a hen tonite and an organic basecontaining 10 to 20 carbon atoms, namely, octadecyl amine bentonite,were dispersed in the polymer-containing oil mixture. Two parts byweight of methanol were used in the blending procedure to aid indispersing the octadecyl amine bentonite.

The resistance to leaching by water of the compositions prepared asdescribed above when compared with a sim ilar composition containing nopolymer is shown in the following table:

Composition, percent by Wt.... A B O D E F Lubricating oil base 91.5 90.5 88. 5 86. 5 90. 5 86.5 octadecyl amine bentonite. 6. 5 6. 5 6. 5 6. 56. 5 6. 5 Methanol 2.0 2. 2.0 2.0 2.0 2.0 Polymerizedlauryl-alphamethacrylate concentrate (40 percent active ingredient) 1.03.0 5. 0 Polymerized ethylene 1. 0 w. 0 Water resistance (Rotating rack;water sprayed at rate of 500 cc./min. for 15 min.):

0.0 2. 6 7. 2 l5. 5 19. 7 43. 4 Percent lubricant retention It can beseen from the data in the above table that the compositions B to Fcontaining from 1 to 5 per cent of either polymerized ethylene orpolymerized lauryl-alphamethacrylate concentrate gave remarkablyimproved results with respect to water-leaching characteristics.

This application is a continuation-in-part of our copending application,Serial No. 132,212, filed on December 9, 1949, now abandoned.

While the invention has been described with reference to specificdetails and examples of the production and properties of thecompositions of our invention, it is to be understood that the inventionis not intended to be limited to such details and examples, except asrecited hereinafter in the appended claims.

We claim:

1. A lubricant comprising a dispersion of a compound of a bentonite andan organic base containing 10 to 20 carbon atoms in a solution of an oiland a polymer selected from the group consisting of polymerizedethylene, polymerized esters of acrylic acid, and polymerized esters ofalpha-methacrylic acid, wherein the amount of said bentonite compound issufiicient to produce a composition having the consistency of a greaseand wherein the amount of said polymer is sufiicient to improve thewaterleaching characteristic of said lubricant.

2. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base containing 10 to 20 carbon atoms in asolution of an oil and a polymer selected from the group consisting ofpolymerized ethylene, polymerized esters of acrylic acid, andpolymerized esters of alpha-methacrylic acid wherein said bentonitecompound is present in said lubricant in an amount corresponding toabout 3 to about 20 per cent by weight of the lubricant and wherein theamount of said polymer is suflicient to improve the water-leachingcharacteristic of said lubricant.

3. An improved lubricant comprising a dispersion of a compound of abentonite and an organic, base containing 10 to 20 carbon atoms in asolution of an oil and a polymer selected from the group consisting ofpolymerized ethylene, polymerized esters of acrylic acid, andpolymerized esters of alpha-methacrylic acid wherein said bentonitecompound is present in said lubricant in an amount corresponding toabout 3 to about 20 per cent by weight of the lubricant and wherein saidpolymer is present in said lubricant in an amount corresponding to about0.4 to about 5.0 per cent by weight of said lubricant.

4. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base contaming 10 to 20 carbon atoms in asolution of an oil and polymerized ethylene having a molecular weightbetween about 1,000 and about 30,000.

5. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base containing 10 to 20 carbon atoms in asolution of an oil and a polymerized ester of acrylic acid and amonohydric alcohol containing at least 5 carbon atoms.

6. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base containing 10 to 20 carbon atoms in asolution of an oil and a polymerized ester of alpha-methacrylic acid anda monohydric alcohol containing at least 5 carbon atoms, wherein saidpolymerized ester is present in said lubricant in an amount sufiicientto improve the Water-leaching characteristic of said lubricant.

7. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base containing 10 to 20 carbon atoms in asolution of an oil and a polymerized ester of acrylic acid and astraight chain monohydric primary saturated alcohol containing between 8and 18 carbon atoms.

8. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base containing 10 to 20 carbon atoms in asolution of an oil and a polymerized ester of alpha-methacrylic acid anda straight chain monohydric primary saturated alcohol containing between8 and 18 carbon atoms, wherein said polymerized ester is present in saidlubricant in an amount sufficient to improve the water-leachingcharacteristic of said lubricant.

9. An improved lubricant comprising a dispersion of a compound of abentonite and an organic base containing 10 to 20 carbon atoms in asolution of an oil and a polymerized ester of alpha-methacrylic acid anda straight chain monohydric primary saturated alcohol containing between8 and 18 carbon atoms wherein said bentonite compound is present in saidlubricant in an amount corresponding to about 3 to about 20 per cent byweight of the lubricant and wherein said polymerized ester is present insaid lubricant in an amount corresponding to about 0.4 to about 5.0 percent by weight of said lubricant.

10. An improved lubricant consisting essentially of a uniform mixture ofabout to about per cent by weight of a lubricating oil, about 3 to about20 per cent by weight of octadecyl amine bentonite, and about 1 to about5 per cent by weight of polymerized ethylene having a molecular weightof about 20,000.

11. An improved lubricant consisting essentially of a uniform mixture ofabout 75 to about 95 per cent by Weight of a lubricating oil, about 3 toabout 20 per cent by weight of octadecyl amine bentonite, and about 1 toabout 5 per cent by weight of polymerized lauryl-alphamethacrylate inthe form of a 40 per cent by weight mineral oil concentrate having aviscosity of about 27,500 SUS at F.

References Cited in the file of this patent UNITED STATES PATENTS1,517,577 Olsson Dec. 2, 1924 2,121,606 McCulloch June 21, 19382,448,567 Zisman Sept. 7, 1948 2,467,147 Morway Apr. 12, 1949 2,531,440Jordan Nov. 28, 1950 2,554,222 Stross May 22, 1951 2,583,603 Sirianni eta1. Ian. 29, 1952 2,583,604 Sirianni et a1. Jan. 29, 1952 2,583,605Sirianni et al. Jan. 29, 1952

1. A LUBRICANT COMPRISING A DISPERSION OF A COMPOUND OF A BENTONITE ANDAN ORGANIC BASE CONTAINING 10 TO 20 CARBON ATOMS IN A SOLUTION OF AN OILAND A POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYMERIZEDETHYLENE, POLYMERIZED ESTERS OF ACRYLIC ACID, AND POLYMERIZED ESTERS OFALPHA-METHACRYLIC ACID, WHEREIN THE AMOUNT OF SAID BENTONITE COMPOUND ISSUFFICIENT TO PRODUCE A COMPOSI TION HAVING THE CONSISTENCY OF A GREASEAND WHEREIN THE AMOUNT OF SAID POLYMER IS SUFFICIENT TO IMPROVE THEWATERLEACHING CHARACTERISTIC OF SAID LUBRICANT.